Occupational exposure to Mycobacterium bovis infection in deer and elk in Ontario.

In late 1991, two herds of deer and elk were depopulated at a slaughtering plant in Ontario, followed by processing of infected animals at a rendering plant. We conducted a questionnaire plus tuberculin skin-test survey of 104 exposed slaughtering and rendering plant workers, and government veterinarians and inspectors. Overall, 17 participants were skin-test positive, one of 51 initially skin-test negative subjects tested a second time three months later became positive, consistent with the risk associated with occupational exposure during the depopulation of tuberculous elk previously observed in Alberta. Deer farming is widespread, with 263 herds in Ontario. The likely route of transmission is through aerosols. Possible reasons for the low conversion rate include the use of respiratory protection, absence of a tanning plant, an enclosed rendering plant process, and late skin testing which may have underestimated the number of conversions. Recommendations for prevention are summarized; in particular, respiratory protection for work with infected herds should probably include high efficiency particulate face masks.

Enzootic nasal adenocarcinoma of sheep in Canada.

A survey of veterinary diagnostic laboratories revealed that intranasal tumors occur in sheep in most provinces of Canada. Tumors were diagnosed in 44 sheep of several breeds including Polled Dorset, Suffolk, Cheviot, Rambouillet and various crossbreeds. Twenty-seven percent of tumors occurred in sheep that were less than two years old. Most tumors were sporadic but 33% of cases occurred in six related flocks, indicating that this disease can be an enzootic problem. The clinical signs were persistent serous, mucous or mucopurulent nasal discharge and stridor. Affected sheep progressively developed anorexia, dyspnea and mouth breathing and most died from effects of asphyxia and inanition within 90 days of the onset of clinical signs. Tumors originated unilaterally or occasionally bilaterally in the olfactory mucosa of the ethmoid turbinates. They were expansive and sometimes locally invasive but metastases were not found. Histologically, the tumors were classified as adenomas or, more frequently, adenocarcinomas. The etiology was not established but retrovirus like particles were observed in tumor tissue from one affected sheep.